The invention relates to a multi-wire instrument, in particular, for endoscopes.
Various multi-wire instruments are used, particularly for endoscopes for example, in applications as calculus collecting basket instruments for collecting gall or kidney stones. In their functional condition in the distal functional section, the individual wires form a functional wire mesh in the shape of a small wire basket. The wire basket may also have the function of a snarl or filter unit. Typically, the distal functional section can be pulled into a guiding tube while the functional wire mesh is folded together and can be moved out of the guiding tube again while the functional wire mesh is unfolded. For this purpose, a superelastic material, such as an NiTi alloy, such as nitinol, can be preferably used for the individual wires.
In the case of a current instrument type, the individual wires are proximally guided together behind their distal functional section and are fixed on a proximally continuing shaft wire made of tube or strand material which forms the shaft section of the instrument; see U.S. Pat. No. 6,013,086. When the connection between the proximal ends of the function-forming distal individual wires and the distal end of the shaft wire tears unintentionally, for example, as a result of a tensile load when collecting a calculus, the use of this type of instrument may lead to difficulties.
As a remedy, German Published Patent Application DE 197 22 429 A1 suggests forming the individual wires of the distal functional section by an axial slotting of a solid or tube-shaped unworked wire in regions, which unworked wire acts as a shaft-side tension strand in the unslotted proximal region. While leaving a distal end stub, the axial slotting ends at a distance in front of the distal frontal end of the wire blank on which a, for example, spherical or hemispherical end element may be mounted.
The later Published German Patent Application DE 10 2004 055 375 A1 also describes a multi-wire unit which is made in one piece from a tube piece and has several wire pieces into which the tube piece is divided by way of axial slotting in regions, wherein, while leaving a distal wire connection region, the axial slots end at an appropriately small axial distance. As a result, in the functional condition of the multi-wire unit, the wire pieces form a, for example, small-basket-shaped functional wire mesh and the distal wire connection region is deformed into an essentially tipless forward end.
The later Published German Patent Application DE 10 2005 030 010 A1 describes a calculus collecting basket unit, wherein the basket region is formed by wire pieces, which are guided together at their distal end and are fixed to a distal head piece having a preset breaking point. This has the purpose of achieving that, in the event of an overload when in use, the head piece releases the wire pieces at their distal end, so that an undesirable uncontrolled tearing of other connection points can be avoided and/or a collected calculus can be released again.
The Registered Utility Model document DE 89 04 213 U1 discloses a multi-wire instrument of the above-mentioned type in the form of a lithotripter having a small collecting basket, which is formed of several collecting strands consisting of a wire material and extending in a bent manner toward the outside. The collecting strands converge at the tip of the collecting basket and are connected with a tension strand of several tension wires. The tension strand consists of a twice-twisted wire rope whose litz number corresponds at least to the number of collecting strands of the collecting basket, which are formed by deformed strands of the wire rope, extending from the wire rope to the tip of the collecting basket and being mutually fastened there with their free ends. At a proximal foot region of the collecting basket, the strands of the wire rope are held together by a sleeve in which the possibly existing other strands extending only in the shaft section also distally end. In a portion of the shaft section proximally adjoining the foot section of the collecting basket, the strands are untwisted from one another and extend in an untwisted manner, whereby the tension strand flexibility is to be increased. The strands forming the collecting basket extend in the same manner untwisted in their collecting basket section and in their adjoining distal end region, in which case they are fixed to one another with their free distal ends by way of soldering or clamping while forming a type of predetermined breaking point.
U.S. Pat. No. 6,187,017 B1 discloses a calculus collecting basket instrument having a specific collecting basket design, in which two pair-generating individual wires respectively adjoining the basket-forming section in the distal direction first cross one another while forming a first crossing point, then radially move away from one another again and, subsequently, while forming a second crossing point, are guided together again while crossing one another in order to then, in a purely axial direction, be fixed in an abutting manner to an atraumatic cylindrical terminating body. In this case, at both crossing points, one wire may both times be disposed under or over the other wire or once may be situated over and the other time may be situated under the other wire. The individual wires are fixed with their proximal end directly behind their basket-forming section on a separate shaft body.
Especially for medical applications, for example, for nephrolithotomies, a cross-section or diameter is desirable for the multi-wire instrument that is as small as possible in order to be able to introduce the latter into corresponding tissue canals without any problems. Simultaneously, the functional wire mesh provided by the individual wires has to guarantee the properties required for its function, particularly with respect to stability or strength and flexibility or rigidity.
The invention is based on the technical problem of providing a multi-wire instrument of the above-mentioned type which can be implemented at relatively low expenditures and, as required, with a comparatively small cross-section or diameter also in its shaft section, and in the case of which the danger is minimized that connection points tear in an undesired manner when the instrument is in use.
According to the invention, a multi-wire instrument is provided in which individual wires are joined at the distal end by way of a respective predetermined breaking connection directly to one another or to a distal terminating body and extend in one piece from the distal end to the proximal end region of the multi-wire instrument, the shaft section being formed by the individual wires combined there and held together.
Since the individual wires are implemented in one piece from the distal end to the proximal end region of the multi-wire instrument, there is no additional shaft wire to which the individual wires have to be fixed and, therefore, no connection point of the proximal ends of the individual wires with the distal end of a proximally adjoining shaft section. On the contrary, the individual wires themselves form the entire shaft section in the corresponding region. This eliminates the risk that such connection points undesirably tear during use when stressed. Rather, as a result of the fact that the predetermined breaking connections are provided at the distal end of the individual wires, care is taken that, at these predetermining breaking points, the individual wires can detach in a defined manner at their distal end from the connection point, so that the functional wire mesh formed by the individual wires can open at its distal end. When the instrument is used, for example, as a calculus collecting instrument, this permits a distal releasing of an already collected calculus in the event of an overload, whereby it is avoided that the instrument tears at a different point and parts of the instrument possibly remain in the tissue and/or an excessively large collected calculus can no longer be released. Since the shaft section is formed by the converged individual wires themselves, it can be implemented with a comparatively small cross-section, which essentially corresponds to the sum of the individual wire cross-sections.
According to one aspect of the invention, the individual wires are mutually twisted in the entire shaft section and therefore distally to the transition into the basket-forming functional section. This provides a highly loadable shaft section while the cross-section is comparatively small without the use of additional devices, such as guiding or fixing sleeves or the like.
According to another aspect of the invention, the individual wires are mutually twisted in a distal end region proximally adjoining the predetermined breaking connections such that they rest against one another along this mutual twisting. This measure may be provided in addition or as an alternative to the measure of the twisting in the shaft section that continues distally to directly to the basket-forming functional section and provides an increased loading capacity of the predetermined breaking connection of the distal individual wire ends.
As an advantageous further development of the invention, the individual wires in the basket-forming functional section are untwisted, so that they form a corresponding wire basket there in a mutually untwisted manner in basket wire sections extending in pertaining longitudinal planes.
As a further development of the invention, the distal terminating body has a hemispherical or spherical terminating element, whereby the distal end of the instrument is provided with desired atraumatic properties.
As a further development of the invention, the distal terminating body has a terminating element for fixing the distal individual wire ends as well as a protective sleeve proximally adjoining the terminating element. In the protective sleeve, the individual wires are held with their distal end region. The protective sleeve may have the purpose of providing the respective predetermined breaking connection of the distal individual wire ends with a desired stability, for example, with respect to the bending open of the individual wires into a basket-forming functional condition.
In a further development of the invention, the distally end-side twisting of the individual wires is equal to that in the shaft section; that is, it has essentially the same twisting parameters, particularly an essentially equally large lead of the screw-shaped twisting turns.
In a further development of the invention, the individual wires are fixed with their proximal end directly to one another or to a proximal terminating body and/or, in the proximal end region, are received in a tubular gripping element. This implements advantageous designs of the multi-wire instrument in its proximal end section.
For the individual wires, for example, monofil wire material or stranded wire material can be used.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description when considered in conjunction with the accompanying drawings.